For example, to reduce fuel consumption of an automobile, it has been demanded to reduce the sliding resistances of various sliding members installed in the automobile. Therefore, in some cases, at least a portion of the surface of the base material of the sliding member is covered by a DLC (Diamond-Like Carbon) film with low frictional properties and high wear resistance (high hardness) (for example, refer to Patent Document 1).
The DLC film is formed by, for example, a DC plasma CVD (Plasma Chemical Vapor Deposition) method using application of a DC voltage to the base material or DC pulse plasma CVD method using application of a DC pulse voltage to the base material.
Specifically, the inside of the treatment chamber that houses the base material is vacuum evacuated, and while keeping a predetermined treatment pressure inside the treatment chamber by continuously introducing a material gas including a carbon-based compound such as methane, hydrogen gas, and argon gas, etc., plasma is generated inside the treatment chamber by applying a DC voltage or a DC pulse voltage to the base material Accordingly, ions and radicals are produced from the material gas, and chemical reaction occurs on the surface of the base material, and a film (DLC film) containing C (carbon) as a main component accumulates on the surface of the base material.